Tracing cloth



Ocpzz, 1946. 1 E. .1. STAUD I 2,409,990

TRACING CLOTH Original Fled Sept.l 16, 1943 2 Sheets-Sheet 1 FIG. I.v

' PRINTING LIGI-IT YEL'Low FILTER PAPER NEGATIVE IMAGE OF DRAWING ORTHOSENSITIVE EMULSION A MAGENTA DYED LAYER TRAcING cLoTI-I MAGENTA DYEDLAYER TRAcING cLoTI-I BLUEPRINT PAPER ORTI'IO SENSITIVE EMULSION/NITRATE OR ACETATE, DYED MAGENTA DYE a`TRAcINc; cLoTH BASE A ORTHOEMULSION AND POSITIVE IMAGE WITH SUBSTANTIALLY PERMANENT CYRIL J. STAUDINI/'ENT OR B'Y n V ATTQRNEYS 09.291946. I QJ, STAUD 2,409,990

- TRACING CLOTH Original Filed Sept. 16, 1945 l Sheets-Sheet 2 F'IG.5.

DENSITY A 40o 50o 60o wAvELENGTH, m,L

CYRIL J. STAUD INVENTOR @bmw/.0mm

Patented Oct. 22, 1946 TRACING CLOTH Cyril J. Staud, Rochester, N. Y.

Original application September 16, 1943, Serial No. 502,591. Divided andthis application October 28, 1944, Serial No. 560,873

9 Claims.

The present invention relates to photographic materials and prints madetherefrom, and is a division of my copending application 502,591, filedSeptember 16, 1943. More specifically, the invention relates to asensitized tracing cloth which may be exposed to a drawing or a negativethereof to form an image thereof on the cloth, and which may then beused to print the image onto blue print or other copying paper.

Some diculty has been experienced from time to time in the use ofphotographic tracing cloth as a result of halation produced by thediffuse reflection of light from the cloth into the emulsion, with theresultant widening of the lines in the image of the drawing. Thiseffect, while not usually serious, has in certain cases becomeobjectionable in the aircraft industry.

In order to overcome this diiculty, the present invention proposes thatinstead of using a blue dye in the cloth, as is present practice, anantihalation layer containing a permanent or water insoluble magenta orblueA dye or dye mixture be provided. This dye or dye mixture willabsorb strongly in the green and will be transparent to or will transmitfreely the blue or the blue and red. On a tracing cloth thus colored, anorthochromatic emulsion would be coated. On exposing the emulsion of thetracing cloth to the negative of the drawing, a yellow filter would beused to absorb blue light and transmit red and green. The dye in theantihalationj` layer would absorb any green light which would passthrough the emulsion, and would, therefore, prevent halation thereof andthusprovide a positive image on the cloth which is a true and exactreproduction of the original drawing. `On the:

other hand, blue light would bel freely transmitted by the dye duringthe printing operation, and it would, therefore, be unnecessary toremove this dye from the tracing cloth. By means of this arrangement,the positive image on the trac-` ing cloth may be utilized to print ontoblueprint paper a positive image which is a substantially truereproduction of the Original drawings and superior to reproductions madeby prior methods.

The present invention has, therefore, as its` dye which will effectivelyprotect the emulsion of the member against halation.

Still another object of the invention is the provision 0f a permanentanti-halation material which will absorb the light rays used to exposethe emulsion to prevent halation thereof, but will freely transmit thelight rays used in the `printing operation.

Yet another object of the linvention is the provision of an emulsion andan anti-halation combination which will enable the emulsion to beexposed to form an image thereon by mean of a light of one color, andwhich will enable the printing of the image by means of a light ofanother color.

To these and other ends, the invention resides in certain improvementsand combination of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawings:

Fig. 1 shows the method of printing' a positive image of a drawing ontoa paper negative to form a negative image thereon;

Fig. 2 shows the arrangement of the printing light, the paper negativeand the tracing cloth of the present invention duringexposure of theemulsion of the cloth to form a positive image of the drawing thereon;

Fig. 3 shows the arrangement ofthe printing light, the tracing clothwith its developed and fixed positive image, and the blueprint paper. inposition to have the positive image printed there- Fig. 4 is a sectionalview of the "tracing cloth constructed in accordance with the'presentinvention; and i i Fig. 5 is a spectrophotometric absorption Curve ofone dye suitable for use in the anti-halation layer ofthe clothillustrated in Fig. 4.

. Similar` reference numerals throughout the various views indicate thesame parts.

Referring tothe drawings, Fig. 4 shows a trac` ing cloth constructed inaccordance with the present invention, and comprising a support I l ofuntinted cloth which is rendered translucent or light transmitting inany suitable and wellknown manner. The base ll is coated with an underlayer I2 of cellulose acetateor nitrate containing an anti-halationmateria-lin the form of a dye or dyes which will absorb strongly'in thegreen, but transmit freely in the blue or blue and red. So far as isknown, no satisfactory method has been devised'for incorporating aremovable anti-halation dye of this type in an under layer.

For this reason, the present invention proposes the use of a permanentor water-insoluble dye or dyes which will remain in place during theprocessing of the tracing cloth, and which will lbecome a permanent partthereof. Any dye or dyes meeting these requirements may be used. Forexample, a permanent water insoluble magenta-color dye having thechemical formula 1,4- diamino-Z-methoxyanthraquinona thespectrophotometric absorption curve of which is shown in Fig. 5, issuitable. It is seen from this curve that this dye has a strongabsorption inthe green and also absorbs somewhat in the orange, but iscompletely transparent in the violet to 420 mu and transmits blue freelyto about 460 mu. The cloth base thus colored is coated with' anorthochromatic emulsion I 3. A cloth base thus provided with an underlayer containing a permanent magenta dye and coated with anorthochromatic emulsion will be free from halation when exposed by greenlight.

The tracing cloth, above described, is intended for use in formingimages of a drawingv or similar designation on a sensitized blueprintpaper or similar material. In making such blueprints, it is desirablethat the lines thereon be substantially identical to those of theoriginal drawings. To secure this' result, a negative is iirst made ofthe drawing, and then the orthochromatic emulsion layer I3 of thetracing cloth is exposed to the negative to form an halation-freepositive image which is an exact reproduction of the original drawing.This positive image is then transferred, by printing, onto the blueprintpaper to provide av substantially true and accurate reproduction of theoriginal drawing which may then be used` as a working drawing in amanner well known. By means of this method, the blue prints aresubstantially exact reproductions of the original drawings and are moreaccurate than blue prints made by prior methods.

Figs. 1 to 3 show the various steps in the formation of the finalpositive image of the blueprint paper. In Fig. l, the drawing paper Iwith its drawing or image I6 is placed on a suitable negative paper IIsuch as Kcdalith negative paper, having an emulsion layer I8. Theprinting light I9 is then passed through the drawingin the manner shownin Fig. l to expose 'the emulsion I8 to form a negative image of thedrawing I i5 thereon, as is apparent. The negative image in the emulsionI8 is then developed and fixed in the manner well known in the art.

The negativev is then arranged to overlie theV tracing cloth, see Fig.2, so that the visual negative image 2I thereon engages the emulsionlayer I3l of the tracing cloth. For the purpose of clarity the negativeand tracing cloth are shown slightly separated, but it will beunderstood that in practice they are in actual contact. Ay yellow lter22 is used during exposure and is positioned between they exposing light23 and the paper negative. This yellow filter will absorb blue, but will4freely transmit green and red. The transmitted green light will exposethe orthochromatic emulsion, which is green and blue sensitive, to formtherein a latent positive image of the original drawing I6, as will beapparent. The green light which is effective in exposing the emulsion I3passes through the latter and is absorbed by the above-mentioned magentadye in the under layer I2, thus effectively preventing halation of thepositivefimage in the emulsion I3 on the tracing cloth to provide asharp, clear and true reprotransmitted by the emulsion may be allowed topass through the layer I2 as the emulsion is not sensitive thereto, or,if preferred, the anti-hala'- tion dye or dyes may be blue, absorbingboth green and red light. Thus, the emulsion layer I3 of the tracingcloth is exposed by a light of one color (green) to form' a latentpositive image of the drawing It. The latent positive image is thenvdeveloped and fixed to provide a visual ,positive image 25.

The tracing cloth with its positive image 25 is then positioned in themanner shown in Fig. 3, on aA blueprint paper 26 having a blue or violetsensitive coating or emulsion 2l. For the purpose of clarity the tracingcloth and blueprint paper are shown. slightly separated. In actualpractice they are in direct contact. A white printing light 28" is thenpassed through the 'tracing cloth, in the manner clearly shown in Fig.3, to print the positive image 25v onto the emulsion layer 2l to formthereon a positive image whichY is substantially identical with thepositive image 25 on the tracing cloth. During this passage of theprinting light through the tracing cloth, the dye -or dyes in the underlayer I2 will absorb the light rays of the green portion of the spectrumbut will freely pass or transmit the blueor blue and red rays. eiectivein exposing or printing the emulsion on the light sensitive layer 2', asis apparent. Thus, the printing of the blueprint paper is secured byexposing the emulsion layer El thereof to alight of another color, blue,which is not absorbed by layer I2. After the printing is complete, theimage on the .blueprint paper is'developed` and iixed to provide apositive image which is a substantial duplication or reproduction of theimage ofthe original drawing. The blueprint may then be used as workingdrawing, the advantages of which are apparent to those skilled in theart.

By means of thev above method, the image I6 of the drawing may beaccurately transferred'v to the vblueprint paper 25 to provide a workingdrawing, the lines of which are substantial duplicates of theoriginal-drawings. Furthermore,- the inclusion of the permanent magentadye in the under layer I2 serves to prevent halation of the emulsionlayer I3, yet freely passes or transmits the light rays utilized in theprinting operation.

While one embodiment of the invention. has been disclosed, it is to beunderstood that the inventive idea may be carried out in a number ofways. 'Ihisl application is, therefore, not to be limited to the precisedetails described, but is intended to cover all variations andmodifications thereof falling within the scope of the appended claims. YY

I claim:

1. The process of forming a positive photographic print on a materialwhich is sensitive to only one region of the visible spectrum,comprising, providing a printing member` havingfan` emulsion which issensitive to Ysaid one region andiat least to another region and havingan anti-halation layer which is transparent to light rays of said oneregion but which will absorb lightrays Y said emulsion, exposing saidemulsion to a nega-V tive by means of a light containing light rays ofsaid other region to Vform a positive image on said emulsion, developingand xing said positive image, and printing said positive image onto saidmaterial by exposing the image to lig-ht rays of said one region whichare freely trans- The transmitted blue rays are then,

mitted by said anti-halation layer to produce a positive image on saidmaterial.

2. The process of forming a positive blue print having a coatingsensitive only to the blue region of the spectrum, comprising, providinga printing member having an emulsion which is sensitive to the blueregion of the spectrum and is sensitive to light rays in other regionsof the spectrum and having an anti-halaton layer which is transparent tolight rays in the Iblue region but which will absorb light rays of saidother regions to protect the emulsion against halation, exposing saidemulsion to a negative by means of light rays in said other regions toform a positive image on said emulsion, developing and xing said image,and printing said positive image onto said blue print by exposing theimage to a blue light which is freely transmitted by said layer toproduce a positive image on said blue print.

3. The process of forming a positive blue print on a materail having acoating sensitive only to the blue region of the spectrum, comprising,providing a printing member having an orthochromatic emulsion, and alayer containing a dye capable of absorbing green light to protect theemulsoin against halation but permitting the free pass of blue rays,exposing said emulsion to a negative by means of green light to form apositive image in said emulsion, developing and xing said positiveimage, and then printing said positive image onto said material byexposing said image to a blue light to form a positive image on saidblue print material.

4. The process of forming a positive photographic print on a materialwhich is sensitive only to the blue region of the spectrum, comprising,providing a printing member having an emulsion which is sensitive to theblue and green regions of the spectrum, and also having a layercontaining a dye sensitive to Iblue and red, exposing said emulsion to anegative by means of a green light to form a positive ima-ge in saidemulsion, developing and xing said positive image, and then printingsaid positive image onto said material by exposing said image to a bluelight to form a positive image on said material.

5. The process of forming a positive photographic print on a materialsensitive to only the blue region of the spectrum, comprising, providinga negative, providing a printing member having an emulsion which issensitive to the blue and green regions of the spectrum, exposing saidemulsion by passing a green light through the negative and the emulsionto expose the latter, allowing said light to then pass into a layercontaining a magenta dye which will absorb the green light to preventhalation of said emulsion but which will freely transmit blue light,developing and nxing the emulsion on said member, and then printing onsaid material by passing a blue light through said emulsion and dyelayer.

6. The process of forming a positive photographic print on a materialsensitive to only the blue region of the spectrum, comprising, providinga negative, providing a printing member having an emulsion which issensitive to the blue and green regions of the spectrum, exposing saidemulsion by passing a green light through the negative and the emulsionto expose the latter, allowing said light to then pass into a layercontaining a magenta anthraquinone dye which will absorb the green lightto prevent halation of said emulsion but which will freely transmit bluelight, developing and xing the emulsion on said member, and thenprinting on said material by passing a blue light through said emulsionand dye layer.

'7. The process of forming a positive photographic print on a materialsensitive to only the blue region of the spectrum, comprising, providinga negative, providing a printing member having an emulsion which issensitive to the blue and green regions of the spectrum, exposing saidemulsion by passing a green light through the negative and the emulsionto expose the latter, allowing said light to then pass into a layercontaining e, magenta alkoxy anthraquinone dye which will absorb thegreen light to prevent halation of said emulsion but which will freelytransmit blue light, developing and xing the emulsion on said member,and then printing on said material by passing a, blue light through saidemulsion and dye layer.

8. The process of forming a positive photographic print on a materialsensitive to only the blue region of the spectrum, comprising, providinga negative, providing a printing member having an emulsion which issensitive both to the blue and the green regions of the spectrum,providing a yellow lter which will pass green and red but which willabsorb blue, exposing said emulsion by directing a white light onto saidfilter so that only green and red light are transmitted to the emulsionto expose the latter, providing said member with a layer havingincorporated therein a permanent dye which will absorb light of thegreen region after the passage thereof through said emulsion to preventthe halation thereof but which will freely transmit blue light,developing and xing the exposed emulsion, and then printing on saidmaterial by passing a blue light through said emulsion and dye layer.

9. The process of forming a positive photographic print on a materialsensitive to only the blue region of the spectrum, comprising, providinga negative, providing a printing member having an ortho-chromaticemulsion, providing a yellow filter Which will pass green light but willabsorb blue, exposing said emulsion to green light by directing a whitelight onto said lter positioned between the light and emulsion,providing said member with a layer having incorporated therein a,permanent dye transparent to blue but capable of absorbing in the greenregion of the spectrum so as to absorb the green light after the passagethereof through said emulsion to prevent halation thereof, developingand xing the exposed emulsion, and then exposing the printing member toWhite light the greenportion of which will be absorbed by said dye butthe blue portion of which will be freely transmitted to expose saidmaterial.

CYRIL J. STAUD.

